Guidance device for thermo shrinkable film machine

ABSTRACT

A shrinkable film machine includes a lower pulley and an upper pulley so as to feed the shrinkable film to a control unit located between a shaft and the upper pulley. The control unit includes a detection part and a transferring part. The guidance device includes two side walls and a slot defined therebetween so that the film passes through the slot before being mounted to the shaft. The two side walls extend through the detection part so that the film is guided before entering the transferring part.

FIELD OF THE INVENTION

The present invention relates to a guidance device for a thermo shrinkable film machine so as to guide the film to be mounted to the shaft correctly.

BACKGROUND OF THE INVENTION

A conventional thermo shrinkable film machine 1 is disclosed in FIGS. 1 and 2, and generally includes a lower pulley 10 and an upper pulley 11 so as to transfer the film 2 to the shaft 13 which is located below the upper pulley 11. A control unit 12 is located between the shaft 13 and the upper pulley 11 and includes a transferring part 120 having rollers to push the film 2 and a detection part 121 for detecting the movement of the film 2. A cone-shaped top of the shaft 13 and an extension portion extending from the cone-shaped top extend through the transferring part 120 and is ended before the detection part 121, so that the film 2 is mounted to the extension portion and the shaft right after the film 2 passes through the detection part 121. Nevertheless, if the film 2 is suffered by a side wind which blows the film 2 off from the pre-set path and the film 2 enters the detection part at an angle. This results in a larger friction between the film 2 and the detection part 121, and the friction results in a delay of feeding of the film 2. The delay makes each section of the film 2 to be cut becomes shorter than it is supposed to be.

The present invention intends to provide a guidance device that ensures that the feeding of the film can be controlled normally even if the film is suffered by a side wind.

SUMMARY OF THE INVENTION

The present invention relates to guidance device for a shrinkable film machine and the guidance device includes two side walls which extend through the detection part of the control unit and a slot is defined between the two side walls. The slot is located between the upper pulley and the shaft such that the film enters the slot and is guided between the two side walls before entering the transferring part of the control unit.

The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a conventional thermo shrinkable film machine wherein the feeding of the film is in a normal status;

FIG. 2 shows that the film is blown by a side wind in the conventional shrinkable film machine and the feeding of the film is in an abnormal status;

FIG. 3 shows the guidance device and the control unit of a thermo shrinkable film machine;

FIG. 4 shows the film is fed into the guidance device of the present invention;

FIG. 5 shows the film is blown by a side wind before entering the guidance device of the present invention;

FIG. 5-1 shows an enlarged view wherein the film enters the slot via the entrance portion of the guidance device, and

FIG. 6 is another embodiment of the guidance device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 3 and 4, a shrinkable film machine 1 includes a lower pulley and an upper pulley 3 so as to transfer a thermo shrinkable film 6. A control unit 4 is located between a shaft 7 and the upper pulley 3, and the control unit 4 includes a detection part 41 and a transferring part 40. The shaft 7 includes a cone-shaped top and an extension portion extending from the tip of the cone-shaped top. The extension portion extends through the transferring part 40 so that the film 6 mounts to the extension portion of the shaft 7 after passed through the detection part 41. The transferring part 40 includes two rods 401 and 402 connected between two blocks. Each of the two rods 401, 402 has wheels 403, 404 and adjustment members 405, 406. The two adjustment members 405, 406 have two respective rollers 407, 408 which are located between the two rods 401, 402. The extension portion of the shaft 7 is clamped between the wheels 403, 404 and rollers 407, 408.

The guidance device 5 of the present invention comprises two side walls and a slot 50 is defined between the two side walls. The two side walls extend between the two arms of the detection part 41 of the control unit 4 of the machine 1. Each of the two side walls has a through hole 51 defined therethrough so that the detection sensors (not shown) of the detection part 41 may emit a detection beam (not shown) through the through holes 51 to detect the movement of the film 6. The slot 50 is located between the upper pulley 3 and the shaft 7. Each of the two side walls has an outward leading edge so as to form an entrance portion 501 which includes a divergent opening communicating with the slot 50. The shape of the entrance portion 501 can also be composed of two facing curve surfaces.

Referring to FIGS. 5 and 5-1, if the film 6 is blown by a side wind and the section of the film 6 between the upper pulley 3 and the guidance device 5 is blown off, the film 6 can still be guided into the slot 50 via the entrance portion 501. The film 6 is fed in a straight path in the slot 50 before entering the detection part 41 and the transferring part 40. By the guidance device 5, the shortcoming of the conventional thermo shrinkable film machine can be overcome.

FIG. 6 shows that the guidance device 5 can be made from a one-piece member and the through hole 521 is drilled transversely through the one-piece member.

While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention. 

1. A guidance device for a shrinkable film machine which includes a lower pulley and an upper pulley, a control unit located between a shaft and the upper pulley, the control unit having a detection part and a transferring part, the guidance device comprising: two side walls and a slot defined between the two side walls, the two side walls adapted to extend through the detection part, the slot adapted to be located between the upper pulley and the shaft.
 2. The device as claimed in claim 1, wherein the guidance device includes an entrance portion which includes a divergent opening.
 3. The device as claimed in claim 2, wherein each of the two side walls has an outward leading edge so as to form the entrance portion.
 4. The device as claimed in claim 1, wherein each of the two side walls has a through hole defined therethrough. 